Multiple fuel burner



ET AL Sept. 9, 1958 J. s. 'ZINK, JR.,

MULTIPLE FUEL BURNER Filed D90. 25, 1956 INVENTORS JOHN s znvx JR.ROBERT P nun/d4 ORWLLE REDWARDS ROBERTQREE'D ATTORNEY United StatesPatent MULTIPLE FUEL BURNER John S. Zink, Jr., Robert 1. Duncan, OrvilleP. Edwards, and Robert D. Reed, Tulsa, Okla, ass-ignore to John ZinkCompany, Tulsa, Okla, a corporation of Delaware Application December 26,1956, Serial No. 630,615

3 Claims. (Cl. 158-11) The present invention relates to fuel burners andmore specifically pertains to industrial equipment for burning liquidand gaseous fuel wherein the capacity is enlarged without increasing thedimensions of the burner assembly.

It is known in the art to which the invention pertains to provide aliquid fuel burner at the center of a burner structure with a pluralityof gaseous fuel burners disposed about the liquid fuel burner and toprovide a shroud arranged about the atomized fuel issuing from theliquid nozzle so as to prevent secondary air from moving directly intothe presence of the liquid fuel nozzle. A shroud of the ceramic type forsuch purposes is disclosed in application Serial No. 555,468, filedDecember 27, 'l955, owned by the assignee of the present invention. Inorder to maintain ample free area for the flow of secondary air in theburners of the prior art particularly when a thick walled shield isprovided for the oil burner nozzle the overall structure of the burnermust be increased to maintain proper free area for .air flow in theburner for a given capacity. i

An object of the present invention is to provide a shield enshroudingthe liquid fuel nozzle having a relatively thin wall so as to increasethe free area for secondary air and to thus reduce the overalldimensions of the burner without reducing the capacity or the heatoutput of the burner assembly.

A further object of the invention is to provide a multiple fuel burnerwherein a given quantity of fuel may be more rapidly consumed and aburner wherein the liquid component of the fuel is burned at a higherrate and with a shorter flame than has previously been possible withburner structures of the type to which the invention pertains.

Another object of the invention is to provide a multiple fuel burnerwherein there is more rapid mixing of the secondary air with the fuel atthe desired zone to provide more stable operation of the liquid fuelburner and to shorten the length of the flame produced thereby.

A further object of the invention is to provide improvements in theshape of the tile into which the burning fuel from the liquid fuelnozzle and the gas burners is discharged and to provide a refractoryelement which may be shipped with the burner and erected therewith without the necessity of requiring separate shipment and installation ofseveral burner blocks.

A still further object of the invention is to provide for the dischargeof gaseous fuel downstream and circumferentially along an inner face ofthe refractory tile so as to maintain it at a high temperature and tothereby maintain a high temperature in the combustion area of the burnerassembly and to avoid loss of heat from the flame and to therebyaccelerate the combustion rate of the fuels and to release the maximumof heat into the structure to be heated.

Another object of the invention is to provide an annular shoulder withinthe refractory element so as to deflect the air in the presence of thegas burner tips to 2,851,093 Patented Sept. '9, 1958 ing and thefollowing detailed description wherein an embodiment of the invention isdisclosed.

In the drawing:

Fig. 1 is an axial sectional View of a burner assembly embodying theinvention.

Fig. 2. is a transverse sectional view taken on the line 22 of Fig. 1. i

Fig. 3 is an enlarged fragmentary section of a portion of the shroudwith one of'the gas burners shown in plan.

Fig. 4 is an enlarged sectional view of one of the gaseous fuel burnertips taken onthe line 4-4 of Fig. 3.

Referring to the drawing there is shown at 10 a wall such as the bottomof a structure to be fired. The bottom wall 1%) or floor of a furnace isprovidedwith a cylindrical opening 11 for accommodating a generallycylindrical shape ceramic or refractory shroud member 12. The refractorymember may be supported within the opening 11 by means of a sleeve 14.This sleeve may be supported on the furnace structure by a ring-shapedbracket 16 which may be secured to the wall 10 in any suitable manner.The sleeve 14 is provided with an end wall 17 on which the refractorymember 12 rests and the end wall 1'7 provides means to which otherportions of the burner structure as hereinafter described may beattached.

The inner surface of the refractory member 12 is of cylindrical shapethroughout the downstream end thereof as shown in Fig. 1. A plurality ofcircumferentially extending shoulders 19 are provided on the interior ofthe ceramic member 12 near the upstream end. These shoulders provide asubstantially annular rib with spaces 21 therebetween for accommodatingthe gas burner tips as hereinafter described. The circumferentiallyextending shoulders 19 may be formed integral with the refractoryelement 12.

An annular member 23 is disposed below the refractory element 12 andcloses the opening in the upstream end thereof. The annular member 23carries a flange 24 which is of ring shape and may be secured to the endwall 17 of the sleeve 14 in any suitable manner such as by means of capscrews. The upper end of the annular member 23 fits within the lower endof the shroud 12 and is in abutting relationship with the annular ribstructure. A cylindrical member 26 is arranged below the annular member23 and in abutting relationship with the lower end thereof. Thecylindrical member 26 is provided with circumferentially spaced openings27 and forms the stationary part of an air register. An end plate ordisc 28 closes the free end of the member 26 and this disc is secured tothe annular member 23 by means of cap screws 31 which extend throughspacer elements 32. The disc 28 is thus maintained in rigid assemblyrelationship with the burner structure. A sleeve 33 is provided aroundthe member 26 and may be rotated thereon by means of a handle 34. Thesleeve 33 is provided with openings which are circumferentially spacedto provide an air register wherein the openings of the rotatable sleeve33 may be brought into registration with the openings 27 and the volumeof secondary air may thus be controlled.

A gaseous fuel manifold 36 of an annular type is secured to the disc 28in any suitable manner. An inlet opening 37 is provided in the manifoldfor introducing unpremixed gas into the manifold for distribution to thegaseous burner tips as hereinafter described. The disc 28 is providedwith an axially extending flange 39 around a central opening therein. Acylindrical shaped shroud 41 is arranged axially of the burner structureand maintained in position by set screws or the like (not 3 shown) whichare carried by'the flange 39. The shroud 41. may be formed as twotubular parts as shown in Fig. 1 or as a single unitary member. Animportant feature of the shroud structure is that the cylindrical wall18 of small thicknessin relation to theprior art.

A primary air register is supported at the lower end of the shroud 41'and includes a stationary sleeve 43 provided with afiange at its upperend secured to the lower end of the shroud structure 41. Anouter sleeve44 is rotatable on the sleeve 43 so that circumferentially spacedopenings in these two sleeves may be brought into partial or fullregistration as desired for controlling the volume of primary A tube 46is supported by the lower end of the primary air register and extendsaxially therethrouglr andinto the shroud 41. An oil supply pipe 47extends through the tube 46 and a liquid fuel nozzle 48 provided at theinner pnd of the pipe 47 for discharging liquid fuel such as oil throughports in the nozzle 48. It. will: be observed that the nozzle 48 issupported within the burnerassembly and upstream from the downstream endof the shroud 41. The tube 46 is supported in position by means of aring 49 carried by the primary' air register structure.

A gas burner tip 51 is mounted within each space 21 provided betweenadjacent ends of the arcuate shoulders 19. The burner tips 51 aresupplied with gas from the manifold 36 by supplypipes 52. Each burnertip 51 is provided witlrat least two discharge orifices 53 and 54 asshown in Fig. 3. These discharge ports are so disposed that gas from theport 54 is discharged at an angle of approximately sixty degrees withrespect to the axis of the associated supply pipe 52. The included anglebetween the axes of the ports 53 and 54 is approximately ninety degrees.as shown in Fig. 3. The unpremixed gas is thus discharged through theports 53 and 54 so as to travel in a direction which is generallyparallel to the inner surface of the shroud 12 and the gas streams moveboth forwardly towards the space to be fired and also tangentially withreference to. the inner surface shroud 12. Air is drawn into the gas byvirtue of the lower pressure area adjacent the gas streams issuing fromthe ports 53 and 54'and the gas is supplied to the manifold 36 atpressures in excess of three pounds. Such a structure produces a sheetof burning gas in close proximity to the inner surface of the refractoryshroud 12. circumferentially extending shoulders 19 deflect the airmoving: into the presence of the gas burner tips. These eddycurrentstend to stabilize burning of the gas as it moves downstream ofthe burner structure. ing gas isin contact with the-inner surface of therefractory member which is heated to a high temperature. Loss of heatfrom the burningfuels is thus reduced and the flame temperature withinthe burner structure is maintained at ahigh level and the burning ofboth fuels and particularly the liquid fuel is accelerated.

The discharge ports for the liquid fuel burner 48 are so disposed thatthe atomized liquid clears the down stream end of the shroud 41. In viewof the thin wall forming the shroud 41 the included angle between theconical periphery of the atomized liquid fuel as represented by thephantom lines in Fig. 1 may be as great as fifty-five degrees 50- as toprovide a relatively short flame for the burning liquid fuel withouthaving the liquid fuel engage the inner periphery of the ceramic shroud12.

It will. be appreciated that the path or paths for the secondary airentering'through the openings 27 is of shorter length than is the casewhen the shroud around the liquid fuel burner has a thick wall. Thesecondary air moves radially inward over the downstream end of The Theburn- .4 the shroud 41 into the presence of the burning liquid fuel. Thethincharacter of the wall. of the. shroud 41 pluslhe higher includedangle of the liquid fuel spray tends to shorten the flame and accelerateburning of the liquid fuel. Thus more fuel is maintained within theconfines of the burning structure to assist in maintaining the ceramicmember 12 at high temperature which further promotes rapid burning ofboth fuels.

While the invention has been described with reference to specificstructural elements and with regard to one organization includingmembers formed of various materials it will be appreciated that changesmay bemade in the assembly and in the combination. Such modificationsand others may be made without departing from the spirit and scope ofthe invention as set forth in the appended claims.

What we claim and desire to secure by Letters Patent 1. In a multiplefuel burner assembly, a refractory member having a cylindrical innersurface, a plurality of circumferentially extending shoulders projectinginwardly from said inner surface of said refractory member adjacent theupstream end thereof, said shoulders having spaces between adjacent endsthereof, a gas burner tip mounted within each of said spaces, means forsupplying gaseous fuel under pressure to said burner tips, a nozzlelocated centrally of said burner tips, means for supplying liquid fuelto said nozzle, a shroud of cylindrical shape surrounding said nozzle,said shroud having a wall thickness not greater than one-half an inch,means for controlling the volume of air admitted to the exterior of saidshroud for movement over the downstream end thereof into the presence ofthe fuel issuing from said nozzle,.and each of said burner tips havingports for discharging the gaseous fuel along the inner surface of therefractory member.

2. In a multiple fuel burner, a refractory member having a cylindricalinner surface, a plurality of circumferentially extending shouldersprojectinginwardly from said inner surface, said shoulders having spacesbetween adjacent ends thereof, a gas burner tip mounted within each ofsaid spaces, means for supplying gaseous fuel under pressure to saidburner tips, a liquid fuel nozzle located centrally of said gas burnertips, a shroud of cylindrical shape surrounding said liquid fuel nozzle,means for controlling the volume of air admitted to the exterior of saidshroud for movement over the downstream end thereof into the presenceofthe fuel issuing from said nozzle, said burner'tips having. dischargeports therein, said ports being disposed to discharge the gaseous fuelat an angle of approximately sixty degrees with respect to the axis ofthe tip and towards the inner surface of said refractory member.

3. In a multiple burner according to claim 2, wherein eachburner tip isprovided with two diverging discharge ports with the axes'thereofdisplaced by approximately ninety degrees for directing the gaseous fuelin circumferentiallyopposite directions along the inner surface of therefractory member.

References Citedin the file of this patent UNITED STATES PATENTS1,687,390 Ritter Oct. 9, 1928 1,797,570 Ferguson Mar. 24, 1931 1,912,730Schrader June 6, 19.33 2,124,175 Zink July 19, 1938 2,220,572 Knupp Nov.5, 1940 2,661,056 Kuehne Dec. 1, 1953

